Jake Arrieta's Very Real Breakout Gives Cubs an Ace to Build Around

There's what Jake Arrieta used to be, and then there's what Jake Arrieta is.

It's an important distinction to make. What Arrieta used to be is a major disappointment. What he is now, however, is an ace-level pitcher who should be a rock in the Chicago Cubs' rotation for years to come.

Wednesday will mark the one-year anniversary of the Cubs acquiring Arrieta—along with Pedro Strop—from the Baltimore Orioles for veteran right-hander Scott Feldman. For the Cubs, the trade meant swapping a successful reclamation project for a longer-term, higher-ceiling reclamation project.

Arrieta had racked up a 5.46 ERA in parts of three seasons with the Orioles, but he had been a top-100 prospect as recently as 2010 and was still only 27.

"We think Arrieta, getting him out of the American League East and getting him into our environment, we're hopeful he can turn the corner," said Cubs general manager Jed Hoyer, via ESPN.com.

The now-28-year-old right-hander showed progress with the Cubs in 2013, posting a respectable 3.66 ERA in nine starts. If nothing else, it was something to build off.

And man oh man has he built off it in 2014.

After flirting with a perfect game against the Cincinnati Reds on June 24, Arrieta flirted with a no-hitter in a 2-0 Cubs win over the Boston Red Sox Monday night. And though he settled for 7.2 innings of one-hit, shutout ball, he still wrapped up the most impressive June of any pitcher this side of Clayton Kershaw.

Because of how big a problem walks had been for him, what might stand out the most is Arrieta's improved walk rate. That's what happens when a guy goes from a 61.2 strike rate to a 63.8 strike rate.

And it's how this has happened that's really interesting.

Rather than simply hitting the strike zone, Arrieta now seems more interested in living on the edges of the zone. BaseballSavant.com can tell us that he's gotten pretty good at that, and that site and FanGraphs can tell us how he's also enjoyed two corresponding benefits: more called strikes and more swings outside the zone.

Like so:

Jake Arrieta's Strike Zone Manipulation: 2010-2013 vs. 2014

Span

Edge of Zone%

Outside Called Strike %

Outside Swing %

2010-2013

33.5

5.3

29.6

2014

36.9

6.0

31.7

BaseballSavant.com and FanGraphs

How is Arrieta doing it, exactly?

Well, these things are usually mechanical in nature. Arrieta's improvement, apparently, is no different.

“Probably 90 percent of pitching for me as a starter is really getting in tune with your body and being able to repeat a delivery a hundred times in a row,” Arrieta recently told ESPN Chicago's SahadevSharma. “And really, that’s the goal. If you can repeat a delivery consistently, you’re gonna see the benefits of that in your command."

Arrieta indeed has done a better job of repeating his delivery. We can tell that by using TexasLeaguers.com to compare his 2012-2013 release points:

What you see above is a much tighter cluster than in the 2012-2013 graphic. Arrieta's release-point consistency isn't on par with the game's top mechanical hurlers just yet, but it's definitely better.

There's where his improved command is coming from. And while that also helps explain how he's gotten harder to hit, another equally important explanation there has to do with Arrieta's new pitch selection.

The one thing Arrieta always packed before 2014 was good heat. And he still does, as FanGraphs has him 17th among starters (minimum 60 innings) with an average fastball of 93.5 miles per hour.

But Arrieta no longer relies so heavily on his hard stuff. Whereas he never threw fewer than 60 percent fastballs between 2010 and 2013, he's now throwing only 51.3 percent fastballs.

According to Brooks Baseball, part of that entails Arrieta throwing four-seamers less frequently than ever. Per the pitch-type benchmarks Harry Pavlidisoffered at Hardball Times, four-seamers have easily the lowest ground-ball rate and easily the highest fly-ball rate of all pitches. As such, we're looking at a solid explanation for Arrieta's increased ground-ball habit and decreased home run habit.

Brian Kersey/Getty Images

Arrieta had never thrown his slider more than 16.8 percent of the time this year.

But the big change in Arrieta's pitch selection concerns the use of his slider, which has skyrocketed to a career-high 25.9 percent.

And rightfully so.

Arrieta has a pretty good curveball and changeup, too, but his slider is especially nasty. That's largely because of how, per the Baseball ProspectusPITCHf/x leaderboards, his is the fastest slider among starters this year at an average of 89.9 miles per hour. It's a slider with cutter speed.

That's probably why you often hear his slider referred to as a cutter. But the man himself called it a slider in talking to Sharma, and he also explained why he's suddenly using it so much.

“The change of plane is something that obviously yields more swings and misses,” Arrieta said. “What that depth allows you to do is miss a lot more barrels and get a lot more swings and misses. It’s just something that I’ve kind of toyed around with with different grips and different ways to throw it and it’s just become very comfortable for me.”

The numbers suggest Arrieta does have a different slider in 2014, and that missing bats has indeed been its specialty:

Jake Arrieta's Slider: 2010-2013 vs. 2014

Span

Velo

Swing%

Whiff/Swing%

AB/K

AVG

2010-2013

87.6

46.5

26.4

13.7

.222

2014

89.9

55.7

28.5

9.0

.143

Brooks Baseball

Pretty good stuff, this. And for the record, the 30 strikeouts Arrieta has picked up on his slider are out of 74 total. That would be one-fifth of his pitches picking up about 40 percent of his strikeouts.

If you want the ingredients for Arrieta's breakout in a nutshell, here they are: He's gone from having Ubaldo Jimenez-ish command to having Greg Maddux-ish command, and what was already a very good arsenal of stuff now revolves around one unhittable offering in particular.

That's not how all breakouts happen, but it's definitely worked for Arrieta. And since he's still just 28 years old, he should be able to ride his breakout through several more prime years.

And that's a happy thought for the Cubs.

It wasn't that long ago that it didn't look like the Cubs were going to have an ace-type starting pitcher in their long-term plans. The best hope on that front involved signing Jeff Samardzija to an extension, but he's made it clear enough he's not interested.

Rather than watch him leave as a free agent after 2015, the Cubs will more than likely trade Samardzija ahead of the July 31 non-waiver trade deadline. Fellow right-hander Jason Hammel—who's on a one-year deal anyway—is also likely to be dealt, leaving the Cubs with Arrieta, Travis Wood, Edwin Jackson and spare parts for their starting rotation going forward.

Thanks to Arrieta's breakout, that doesn't sound like nearly as dire a situation as it might have been. He's turned into a terrific pitcher, and he's under Chicago's control through 2017.

If the Cubs aren't aggressive in extending Arrieta even further, they could probably do so later. Jackson's $52 million contract will finish in 2016, and the arrival of Kris Bryant, Javier Baez and others in the next few years should help convince Arrieta that Chicago's North Side is a good place to be.

The Cubs acquired Arrieta hoping that he would turn into a part of the team's future. What he's done instead is turn into a big part of the team's future.